so im in physics now and i could use some help (re: SOS)

[Donut]

the problem is about pyramids. the actual problem reads:

The great pyramids of cheops in egypt has a square base 230 meters on each side. the faces of the pyramid make an angle of 51º 50' with the horizontal.
there is more to the problem obviously, but im already stuck on 51º 50'. i have no idea what that is or what it means. can anyone clear this up for me? google isnt very helpful on this particular topic

also how do i apply 51º 50' to a 4 sided pyramid? i have a rough idea, but i cant be sure if im right before i know what 51º 50' is

[jngrow]

Each "edge" is at a 51 degree angle, 50 meters long? I assume meters because EWW WTF FEET IN PHYSICS THAT IS NASTY.

e: nvm, can't help you. iunno about that with the horizantal and stuff. And i never did anything like this in physics.

[OmegaDragon]

51 degree angle edge with a 50 *unit* distance to the tip?
E: Beat to it..

[Donut]

this seems a little fucked up because this is a packet full of problems that i was supposed to be able to do prior to the first day of class. its taken me roughly 8 hours to get to this last problem in the packet, and now i cant even finish it because i dont know what its asking me.

Each "edge" is at a 51 degree angle, 50 meters long?
this is one of the things i originally thought too, but the problem already states that it has a square base with 230 meters on each side

[Phopojijo]

Not sure what the question is asking for -- but I'll explain what you explicitly asked...

51º 50' means 51 degrees and 50 arcminutes. So the angle with the ground is 51+(50/60) degrees... or 51.833333º

So basically you know that the bottom of the pyramid is a 230 meter square.

You also know that the pyramid has 4 sides

Now you also know that the pyramid's height is: (230m/2) tan (51.833333º)

How do you know that? Well -- you have 3 lines:

1) A line from the top of the pyramid to the center of the pyramid's base
2) A line from the center of the pyramid's base to the middle of the pyramid's base's perimeter edge.
3) A line from the pyramid's base's perimeter edge to the top of the pyramid.

(apologies for lack of diagram :p)

Those three lines make a right-angled triangle... right-angled trig says Tan(angle) = Length of Opposite Side / Length of Adjacent side.

Angle is 51.833333º as per the question... length of the center of edge to the center of the pyramid base itself -- is half the length of the edge. Length of Opposite side is the height, which I guess you need to know??

[Kalub]

This^



No one knew about minutes of an angle?

[Donut]

i think i get it. so the 50' is like a way of expressing a non terminating decimal? i understand the 50/60. that makes sense.

either way, all of the information you have me is going to help with this so huge thanks
E: im wondering where in the course of algebra 1 and geometry was i supposed to acquire the knowledge to do something like this.

[Phopojijo]

Not necessarily a non-terminating decimal...

There are 360 degrees in a circle.
There are 60 arcminutes in a degree.
There are 60 arcseconds in an arcminute.

[klange]

Each degree has 60 minutes, each minute has 60 seconds. Much like time.
Sometimes DMS (as it's called...) is used instead of a non-integer degree value.

And then we have radians. Oh, how us mathematicians love radians, but those physicists still don't care for them enough... it makes me sad.

[Donut]

so its like a way of getting really precise angle measures?

[Phopojijo]

Well do you really want to say a decimal number to your colleague during a lab report or something? If you can approximate it to some fraction that everyone can agree on -- why not? 2 or 3 whole numbers might be easier to record than 1 decimal number...

As for radians... Physics uses radians a LOT. Arcseconds are really only used by astronomers in heavy practice because it turns out an arcsecond is about as small of a detail that a common (research-quality) telescope can resolve.

[Donut]

thank you so much for the help. iv got the situation under control now. will rep again when i can